<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>字符串</title>
    </head>
    <body>

        <script type="text/javascript">

            let str1="字符串1";

            let str2 ='字符串2';//相当于： let str2 = new String("字符串2")

            let i =100;
            let str3 =`我有${i}块`;

            console.log(str3);

            var sub = str1.substring(0,3);
            console.log(sub)


        </script>
    </body>
</html>